The present inventive concept relates to nonvolatile memory devices. More particularly, the inventive concept relates to a flash memory device providing a post programming operation in order to improve a pass voltage window and a method of programming the flash memory device.
The nonvolatile memory devices include a variety of resistance variable type devices, including flash memory devices. Contemporary flash memory devices may be generally classified as NAND flash memory and NOR flash memory. NOR flash memory includes memory cells independently connected to bit lines and word lines. NOR flash memory is widely used in applications requiring random data access. In contrast, NAND flash memory includes a plurality of series connected memory cells. Only a single connection contact is required for the resulting cell string. NAND flash memory is thus characterized by very high integration density.
Additional improvements in flash memory integration density have been facilitated by the use of multi-bit memory cells. Multi-bit memory cells operate with two or more threshold voltage distributions, each corresponding to a stored data state. A multi-bit memory cell is commonly referred to as Multi-Level Cell (MLC), and a single bit memory cell is referred to as a Single-Level Cell (SLC).